Submitted to: Current Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/27/2008
Publication Date: 4/1/2008
Citation: Kuo, T., Rooney, A.P., Isbell, T. 2008. Conversion of lesquerolic acid to 14-oxo-11(Z)-eicosenoic acid by genetically variable Sphingobacterium multivorum strains. Current Microbiology. 57:55-60. Interpretive Summary: Surplus vegetable oils represent attractive renewable sources for the production of useful chemicals. Biodiesel is a viable alternative fuel produced from vegetable oils and effective utilization of the by-product glycerol will enhance the long-term self-sufficiency of the biodiesel industry. We are investigating new microbial systems for effectively converting plant lipids and glycerol to produce value-added products. Previously, we found a compost microbial isolate able to modify lesquerolic acid, the dominant fatty acid component of the new crop lesquerella oil, to produce a new product having potential as an improved lubricant ingredient. In this study, we extended the search and identified several strains of the same bacterial species that were able to carry out the biological activity. Additionally, a new culture medium was devised to include glycerol, non-toxic chelating agent, and essential mineral ions to greatly improve the bioconversion process. The impact of this study provides new information and technology for scientists to develop similar bioprocesses and produce value-added products from low cost vegetable oils.
Technical Abstract: We investigated new microbial systems for their ability to convert lesquerolic acid (LQA; 14-hydroxy-11(Z)-eicosenoic acid) to value-added products. A strain of Sphingobacterium multivorum (NRRL B-23212) was found previously to convert LQA to 14-oxo-11(Z)-eicosenoic acid (14-OEA), as determined by gas chromatography-mass spectrometry and nuclear magnetic resonance analyses [Kuo et al. 2007]. Conversion of LQA was subsequently extended to examine S. multivorum and closely related species of Pedobacter, Spirosoma, Chryseobacterium and Flavobacterium. Among 25 of such environmental isolates, a group of bacteria, whose identity was further confirmed by 16S rRNA gene sequence analysis as S. multivorum, was the only species found to conduct LQA conversion to produce 14-OEA. Among these strains, however, NRRL-B-14797 was a variant strain devoid of the specific biological activity. A new culture medium at pH 7.0 was defined to include Fe2+ and Mn2+ mineral ions, glycerol and EDTA•2Na to improve the production of 14-OEA from the initial yields of 2-13% to about 75% and greater for the reactive S. multivorum strains. These S. multivorum strains represent the first group of bacteria reported to carry out the functional modification of LQA.